This accessory is to hold a joystick and break it out into 2 sockets.
You can download this design from the thingiverse page
You need 2 3.5mm sockets, you can buy them here: http://s.click.aliexpress.com/e/boi2MY96
Route 3 cables underneath the square in the middle (there are slots where you can run the cables trough).
Connect the cables to the joystick matching them to the wiring on the PCB/sockets in the PS4 adaptive controller.
Now place a dab of hot glue under the joystick so it sticks in place.
Suggestion: place velcro pads under the print to fix it in place wherever you want it to be.